The present invention relates to a dual voice coil shutter for use in a stepper system, a laser system, and other carefully channeled light devices.
Steppers are well known systems which provide for accurately forming patterns on semiconductor wafers. Such systems are described, for example, in U.S. Pat. Nos. 4,311,494, 4,444,492 and 4,425,037, all of which are commonly assigned to the same assignee as the present invention.
In a stepper environment, it is necessary to accurately control the passage of light hitting a photoresistive wafer through what is known as a reticle. This is frequently implemented with some form of a shutter configuration.
A problem in prior art shutter arrangements utilized in a stepper system is that mechanical oscillations in the structure could cause inaccuracies in mechanical positioning or in the delay of process time while waiting for the oscillations to die out.
Other problems which occur are that prior art shutter implementations require contacting parts that can wear out and cause friction in the activation of the shutter, asymmetric construction which includes different and/or more parts and, finally, a heavy mechanical mass which does not easily provide for fast actuation.